Since no signal in the invariant mass distributions is observed upper limits are estimated. For the estimation of upper limits for the rapidity density d\(N\) /d\(y\)  the method discussed in [1]} is utilised. In particular, we apply the software package \(TRolke\)  as implemented in \(ROOT\)  [2]}. This method needs as input mass and experimental width (3\(\sigma \) ) of the hypothetical bound states. The observed counts are therefore compared to a smooth background as given by an exponential fit outside the signal region (as indicated by the line in Fig. REF  and Fig. REF ). For both candidates \(\overline{\Lambda \mathrm {n}}\)  and H-dibaryon we assume a binding energy of 1 MeV. The width is determined by the experimental resolution and obtained from Monte Carlo simulations. In addition, the final efficiency which is discussed in section  is required.
Further, values of branching ratios of the assumed bound states are needed. These depend strongly on the binding energy. With a 1 MeV binding energy for the \(\overline{\Lambda \mathrm {n}}\)  bound state the branching ratio in the \(\overline{\mathrm {d}}+\pi ^{+}\)  decay channel is expected to be 54% [3]}.
The branching ratio for a 1 MeV or less bound H-dibaryon decaying into \(\Lambda \mathrm {p}\pi ^{-}\)  is predicted to be 64%, see [4]}.
